The manufacturing and fabrication process of sapphire substrate involves orientation z slicing, grinding, chamfering, policing, cleaning, and quality inspection. First, the manufacturer positions the sapphire crystal rod accurately on the slicing machine. Next, the sapphire rod is sliced into thin substrates, and they take further measures to improve its flatness. Next, the substrate edge is cut into a circular arc to enhance its mechanical strength, avoiding defects resulting from stress concentration—polishing and cleaning help remove contaminants from the substrate surface. Finally, using appropriate quality inspection techniques, the manufacturer tests silicon substrate to ensure that it satisfies customer demands and expectations.
A variety of silicon substrate orientations and sizes are available in the marketplace. A-Plane sapphire substrates are typically used in hybrid microelectronic applications requiring consistent dielectric constant and high insulating properties. C-Plane substrates find extensive use in III-V and II-VI compounds, like GaN, to produce bright blue and green LED and laser diodes. R-Plane substrates find use in the hetero-epitaxial deposition of silicon in microelectronic IC products. You can purchase sapphire substrate for use in LED applications. LED remains the dominant sapphire application as it shows better light transmission in the visible range.
Here are some of the essential properties, features, applications, and other essential factors you should know about Sapphire Substrate.
Evaluation Of Substrate Material
When evaluating silicon substrate material, you need to assess the degree of structural matching between the substrate and the epitaxial film. There should be a similarity between the crystal structure of the epitaxial material and the substrate material. It should have low defect density and high crystallization performance. The matching of the thermal expansion coefficient between the substrate and epitaxial film is essential. If it is too large, it can significantly affect the quality of the epitaxial film. The substrate material should have excellent chemical stability, and the preparation of substrate materials requires a certain degree of high conciseness.C-Plane Sapphire Substrate
Sapphire is a single crystal Al2O3 with a hexagonal (rhombohedral) crystal structure. The substrates are available in C, R, A, and M plane orientations. C-plane (0001-orientation) sapphire polished substrates are used for growing gallium nitride or GaN and other III-V and II-VI compounds to manufacture LED. It also finds use in infrared detectors, mercury cadmium telluride, wafer carriers, and general optics. 4 inch and 6-inch substrate wafers find wide adoption by mainstream chip companies.R Plane Sapphire Substrate
R-plane sapphire has a small, energetically unrelaxed geometry over all four surface facets. It is widely preferred for Silicon-on-Sapphire and finds use in semiconductor, microwave, and pressure transducer applications. Manufacturers use it to fabricate active topside Silicon-based devices and topside laser devices. They also use it in the backside polishing of the SOS wafer for manufacturing an optical device on the Silicon side. In addition, R-plane SoS chips work sees extensive use in integrated circuits and photovoltaics.A-Plane Sapphire Substrates
A-plane Sapphire orientations are widely helpful in optoelectronic applications. In addition, it finds use in hybrid microelectronic applications. The two in-plane orientations of GaN are generally possible on the a-sapphire substrate. The orientation is used in the growth of high Tc superconductors. The availability of Angstrom level surface finishes provides fine line interconnects of hybrid modules in the A-plane Sapphire Substrate.Cutting Of Sapphire Substrate
The crystal bar is cut into Sapphire Substrate by wire cutting or multi-wire cutting machine. As the cutting procedure can fluctuate, it can lead to an inconsistency in the thickness and flatness of the cut sapphire, which can cause a deep damage layer. Substrate polishing, grinding is essential for improving the flatness, curvature, and parallelism deviation of the substrate before polishing and for reducing the thickness of the damage layer in the cutting process. The growth and orientation of material and fabrication and polishing of substrates are mapped to form a damage-free material.Properties And Applications
Sapphire substrate shows a combination of high strength, excellent heat resistance, stable electrical properties, wide transmission wavelength range, and excellent thermal conductivity. It is a great electrical insulator and offers good thermal conductivity at low temperatures. In addition, it can retain high strength and chemical resistance at high temperatures. Sapphire can be wetted by glass, titanium, zirconium, or moly-manganese mixtures.Compared to optical materials valuable within its transmission range, sapphire is unique as it is strong, tough, and chemically resistant. You can use it at far higher temperatures than most of the available optical materials. It finds use as a Growth substrate for III-V and II-VI compounds in IR applications, electronics and optoelectronics, Silicon On Sapphire Integrated Circuit(SOS), and Radio Frequency Integrated Circuit (RFIC).
